This invention relates to an indirect dryer for the process of drying copper concentrate in a copper smelter.
The indirect dryer in use in copper smelters is the multicoil steam dryer, where the heat for the drying process is provided by saturated steam supplied through a smelter's waste heat boiler, which uses the thermal energy of the gases of fusion and conversion. However, it is more efficient to use the thermal energy of these gases for electric power generation, while the heat for the drying process is obtained from the cooling of sources like: the smelting and converting furnaces, the slags, the anodes and other sources of heat that at present time are thrown away. The nitrogen generated in the oxygen plant is the natural fluid for transferring the heat from these hot sources to the wet concentrate; but the specific way of how to heat up the nitrogen is not a matter of this application.
The present dryer differs radically from the steam dryer, since the heating of the concentrate is not realized by means of tubes or multicoils. In particular, the problem of wear is not so critical as it is in the multicoil steam dryer. Moreover, the limitation of capacity up to 120 ton per hour that affects the multicoil steam dryer does not arise in this invention.